abc's david wright is in big bear lake. >> suspect vehicle still outstanding. it's a black nissan titan. >> reporter: police officers hunting one of their own. a rogue former officer, now accused of hunting them. >> of course, he knows what he's doing. we trained him. he was also a member of the armed forces. it's extremely worrisome and scary. >> reporter: it all started sunday with a grisly double-homicide. 28-year-old monica quan and her fiance, keith lawrence, shot in their car. a murder with no apparent motive. >> we've identified christopher jordan dorner as a suspect in this double-homicide. >> reporter: 33-year-old christopher dorner, a lieutenant in the u.s. navy reserves, honorably discharged just last friday. fired four years ago by the lapd. police claim he bore a grudge against a retired lapd police captain, randy quan, monica's father, as well as other lapd officers. >> of particular interest at this point in the investigation, is a multipage manifesto. >> reporter: in a rambling manifesto posted online, dorner blames quan and other lapd officers